1. Field of the Invention
The invention relates to a method for periodically emitting mixed light colors from primary color light sources. Moreover, the invention is also directed to a device for implementing the inventive method.
2. Discussion of the Prior Art
Such measures are known from DE 10 2004 047 669 A1 (therein in particular in connection with FIG. 3a and FIG. 4b). According to this document, light sources of the three primary valences (primary colors) red, green and blue, periodically commencing simultaneously, are energized with duty factors which can be set independently of one another and their color emissions are additively mixed. Light sources such as lasers, electroluminescence elements, organic LEDs or in particular semiconductor light-emitting diodes are preferably used since their brightnesses are approximately linearly dependent on the duty factor of the feed with pulse-width-modulated constant current pulses. The resultant mixed light color locus can be represented in the CIE standard chromaticity diagram sketched therein (FIG. 6). This color locus can accordingly be displaced via at least one of the three primary-colored brightness contributions. Each mixed light color can therefore be set within a color triangle which is inscribed in the standard chromaticity diagram and whose corner points are given by the individual color emissions of the three primary-colored light sources used for the mixed light illumination.
Simultaneous switching on of the three light sources within each period can, however, represent a considerable and therefore impermissible pulse load on a system with isolated operation, such as in particular the on-board power supply system of an aircraft, whose passenger cabin is intended to be illuminated with color impressions which vary for example depending on the time of day. At the output of a constant current power supply unit fed from the on-board power supply system for the operation of the light sources, the available energy must therefore be buffer-stored by means of space-consuming and comparatively heavy and expensive stores, in particular electrolyte capacitors.